Check Engine Light

[dually2002]

This is the first trouble I have had with my 02 since I owned it . The check engine light has come on and stayed on. The engine runs fine and everything is normal and has 92765 miles on it. Is there some type of maintenance required that has tripped the light at this mileage. Going to get the code read. Been running a JK tune fore the last 4 years. Stored code PO0380 glow plug related. Cleared code has not returned yet.

[DmaxMaverick]

There are no time, mileage or service related SES lamp events. If it's on, the PCM is complaining about something. Some service interval tasks can cause the SES, but only because of a problem due to improper or the lack of service (such as a plugged air filter).

Don't sweat it until you get the code. Failed glow plugs (P0380) or a dirty MAF sensor (P0101) can cause this, among many other minor things. There are also a bunch of erroneous conditions as well, such as fuel temp (which is usually only a confusion, and not a failure).

[dually2002]

There are no time, mileage or service related SES lamp events. If it's on, the PCM is complaining about something. Some service interval tasks can cause the SES, but only because of a problem due to improper or the lack of service (such as a plugged air filter).

Don't sweat it until you get the code. Failed glow plugs (P0380) or a dirty MAF sensor (P0101) can cause this, among many other minor things. There are also a bunch of erroneous conditions as well, such as fuel temp (which is usually only a confusion, and not a failure).

Thanks for quick reply

[Mark Rinker]

This is the first trouble I have had with my 02 since I owned it . The check engine light has come on and stayed on. The engine runs fine and everything is normal and has 92765 miles on it. Is there some type of maintenance required that has tripped the light at this mileage. Going to get the code read. Been running a JK tune fore the last 4 years. Stored code PO0380 glow plug related. Cleared code has not returned yet.


There is also a 'frail' glowplug harness used on the early engines, if you replace the glowplugs, I'd replace the harness, as well. Up here in 'da nort country', they tend to corrode and break, opening up the power circuit to plugs downline of the break.

[dually2002]

The SES light comes and goes. I do notice that when the light comes on that the volt gauge goes to15 volts imediately after starting as opposed to when the light is off and it reads about 12 for about 15-20 seconds before increasing to 15 volts which is normal. Being itermittent I am thinking more along the line of a bad controller but have not physically checked the system out yet.

[More Power]

The SES light comes and goes. I do notice that when the light comes on that the volt gauge goes to15 volts imediately after starting as opposed to when the light is off and it reads about 12 for about 15-20 seconds before increasing to 15 volts which is normal. Being itermittent I am thinking more along the line of a bad controller but have not physically checked the system out yet.

Sounds glow system or intake air heater related. Both are "emissions" related, and will set a DTC and service engine soon lamp. Otherwise, it will not affect performance. A more serious DTC could result in a limp mode operation - reduced power/rpm.

Jim

[dually2002]

SES light is on continously. Wait to start light cycles normally. Volt metergoes to 15 volts after start. Even in hot weather it would not go to 15 volts that guick when operating normally

[DmaxMaverick]

What's the code? You can waste a lot of time guessing, when you don't have to. If the SES seems related to a real issue you can see, in real time, armchair diagnosis is entertaining, at best.

[dually2002]

The code is P0380

[DmaxMaverick]

Failed glow plugs and/or intake heater......

Check on a cold engine, voltage to a plug connector stud as soon as the key is turned to "ON" (no start). Do the same again with the heater stud. If it shows voltage, the controller and relays are working. No voltage indicates a controller/relay failure. Next, remove the connectors from the heater and plugs (one at a time, or all, but they must be removed from the harness connection), and check the stud to chassis ground continuity with a test lamp or VOM. Any that are "open" (incomplete circuit) is bad. If this is a CA smog truck, you can check individual plugs without removing the connectors. At the top of the controller are two 4-wire connectors, each powering one cylinder bank. Probe the harness for individual plug continuity. There's a pic of the CA glow plug controller and connectors in the "Truck Stuff Pics" in my sig.

P0380 is a "soft" code, meaning it only triggers the SES lamp and sets a code. It doesn't interfere with any running operation of the truck.

[dually2002]

I haven't had a chance to trouble shoot yet but would the Wait to Start indicator cyclic-ling normally indicate that at least some of the glow plugs are working? Cold starts are normal. Also burned a copy of #07057 Special Coverage Adjust -Engine Glow Plugs dated Feb 13 2008 from Alldata. That the extended warranty campaign for glow plugs for 10 years or 200,000 miles. I got 1 month left on the 10 year requirement. Going to take it to the dealer and see what happens.

[DmaxMaverick]

The WTS cycle will be normal, if the problem is only plugs. It's a timed cycle. The GP's aren't necessarily helping with a start, except in the coldest of climates (below zero and such). I've started mine at about -10F with the glow plugs disconnected, intentionally for testing purposes. Started fine, with only about 15 seconds of rough running. Smoothed out to normal after that.

I suggest checking the plugs before you go to the dealer. If it turns out to NOT be the plugs, you'll be on the hook for diagnostic/repair charges. If it is plug(s), let the dealer do them IAW the bulletin, if they will. Some vehicles within the bulletin year models were excluded, so verify yours qualifies before you hand it over.

[dually2002]

Thanks Dmax. Will do.